<?php
/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2011 Oracle and/or its affiliates. All rights reserved.
 *
 * Oracle and Java are registered trademarks of Oracle and/or its affiliates.
 * Other names may be trademarks of their respective owners.
 *
 * The contents of this file are subject to the terms of either the GNU
 * General Public License Version 2 only ("GPL") or the Common
 * Development and Distribution License("CDDL") (collectively, the
 * "License"). You may not use this file except in compliance with the
 * License. You can obtain a copy of the License at
 * http://www.netbeans.org/cddl-gplv2.html
 * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
 * specific language governing permissions and limitations under the
 * License.  When distributing the software, include this License Header
 * Notice in each file and include the License file at
 * nbbuild/licenses/CDDL-GPL-2-CP.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the GPL Version 2 section of the License file that
 * accompanied this code. If applicable, add the following below the
 * License Header, with the fields enclosed by brackets [] replaced by
 * your own identifying information:
 * "Portions Copyrighted [year] [name of copyright owner]"
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 * If you wish your version of this file to be governed by only the CDDL
 * or only the GPL Version 2, indicate your decision by adding
 * "[Contributor] elects to include this software in this distribution
 * under the [CDDL or GPL Version 2] license." If you do not indicate a
 * single choice of license, a recipient has the option to distribute
 * your version of this file under either the CDDL, the GPL Version 2 or
 * to extend the choice of license to its licensees as provided above.
 * However, if you add GPL Version 2 code and therefore, elected the GPL
 * Version 2 license, then the option applies only if the new code is
 * made subject to such option by the copyright holder.
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 * Contributor(s):
 *
 * Portions Copyrighted 2011 Sun Microsystems, Inc.
 */

/**
 * Class managing flash messages.
 * <p>
 * (Flash messages are positive messages that are displayed exactly once,
 * on the next page; typically after form submitting.)
 */
final class Flash {

    const FLASHES_KEY = '_flashes';

    private static $flashes = null;


    private function __construct() {
    }

    public static function hasFlashes() {
        self::initFlashes();
        return count(self::$flashes) > 0;
    }

    public static function addFlash($message) {
        if (!strlen(trim($message))) {
            throw new Exception('Cannot insert empty flash message.');
        }
        self::initFlashes();
        self::$flashes[] = $message;
    }

    /**
     * Get flash messages and clear them.
     * @return array flash messages
     */
    public static function getFlashes() {
        self::initFlashes();
        $copy = self::$flashes;
        self::$flashes = array();
        return $copy;
    }

    private static function initFlashes() {
        if (self::$flashes !== null) {
            return;
        }
        if (!array_key_exists(self::FLASHES_KEY, $_SESSION)) {
            $_SESSION[self::FLASHES_KEY] = array();
        }
        self::$flashes = &$_SESSION[self::FLASHES_KEY];
    }

}

?>
